//设置响应头部
module.exports=async (ctx,next)=>{
    const contentType='application/json; charset=utf-8'
    ctx.set('Content-Type',contentType)
    ctx.response.body=' {"success": true}'
    ctx.set("Access-Control-Allow-Origin","*")
    ctx.set("Access-Control-Allow-Methods","OPTIONS,GET, PUT,POST ,DELETE")
    await next()
}